1. Field of the Invention
The present invention relates to an AV (Audio Visual) system. More specifically, the invention relates to the AV system having a power feeding apparatus for feeding a power and a power receiving apparatus connected to the power feeding apparatus for outputting a contents signal upon supply of the power from the power feeding apparatus.
2. Description of the Related Art
Recently, option units that reinforce the function of AV apparatuses such as AV amplifiers and AV receivers appear on the market. The option units are modules that are externally attached to the AV apparatuses via connectors. Examples of the option units are cradles to which digital audio players (DAP) are detachable and TV tuner apparatuses, radio tuner apparatuses, DVD player apparatuses, CD player apparatuses, and HDD players.
As a method for connecting a plurality of option units to an AV apparatus, daisy chain connection is considered. In the daisy chain connection, as shown in FIG. 1, an AV apparatus 100 and a plurality of option units OPC1 to OPCn (n: natural number) are connected in series with the AV apparatus 100 in the lead. The option unit OPCn is connected to an apparatus before or after itself (the AV apparatus 100 or another option unit OPCn) via a connector. The option units OPC1 to OPCn receive supply of a power from the AV apparatus 100 so as to be capable of operating. That is to say, the AV apparatus 100 serves as a power feeding apparatus, and the option units OPC1 to OPCn serve as power receiving apparatuses.
When the daisy chain connection shown in FIG. 1 is performed, the AV apparatus 100 communicates with the option unit OPCn to be controlled in the plurality of option units OPC1 to OPCn so as to control it. For example, when a cradle to which DAP is attached is connected as the option unit, the AV apparatus 100 makes controls such as selection, reproduction and suspension of contents in DAP via the cradle.
When an AV system adopts such daisy chain connection and a power is always supplied to an option unit, power consumption increases. In order to repress the power consumption, it is preferable that while the operation of the option unit suspends, the supply of the power is repressed. However, even in a case where the power is not supplied, when a new option unit to be controlled is selected or connected, the AV apparatus should detect the option unit to be controlled so as to supply a power thereto.
Japanese Patent Application Laid-Open No. 5-46543 discloses a technology that detects connection of a new option unit while repressing power consumption in a circuit adopting the daisy chain connection system. In the technology disclosed in this document, however, as shown in FIG. 1, option units are not connected in series via a connector.